WELDING RESEARCH A B C D Figure 6 shows that this improvement prevented the cracking shown in Fig. 4, and a sound interface was achieved in the Pd/Ni joint. In addition to the PdSn and Ni3Sn4 intermetallic compounds that formed, a reaction layer with a composition (at-%) of Ag : Sn = 76.5 : 23.5, being consistent 446-s WELDING JOURNAL / NOVEMBER 2016, VOL. 95 with the Ag3Sn intermetallic phase in the Ag-Sn phase diagram (Ref. 18), appeared between the Ni3Sn4 and PdSn. The compositions of Ni3Sn4 Fig. 9 — Microstructure of the Nicoated Pd/Ni couple diffusion soldered at 300°C for 30 min using Sn/Ag/Sn interlayers (Case III). Fig. 10 — Diffusion profile for the Nicoated Pd sheet after preheating at 450°C for 30 min. Fig. 11 — Microstructure of the PdNicoated Pd/Ni couples diffusion soldered at various temperatures for 30 min using Sn/Ag/Sn interlayers (Case IV): A — 275°C; B — 300°C; C — 325°C; D — 350°C.
Welding Journal | November 2016
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